Infections from the diarrhea-causing parasite cyclospora are surging, with state-level data suggesting that 2026 is already the nation's worst year for reported cases.
More than 30 states have reported infections this year, and current data from them shows the number of infections surpassing the record U.S. mark of about 4,700 set in 2019. The illness is not usually life threatening and is typically treated with antibiotics.
Health officials have not yet definitively identified what is causing the infections. On Tuesday, federal health officials said there may be different infection patterns in different places, although they believe cases in at least four states — Michigan, Ohio, Kentucky and West Virginia — are linked.
Michigan officials blame lettuce
In Michigan — where more than 3,300 cases have been reported — officials say early information points to lettuce or salad greens as a possible culprit.
After conducting more than 1,000 interviews with patients, “early information has shown lettuce as a common product that regularly comes up during the investigation,” said Natasha Bagdasarian, the Michigan health department's chief medical executive.
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Because of that commonality and because produce has been behind some past cyclospora outbreaks, Michigan officials advised consumers to buy whole heads of lettuce, discard the outer layers and thoroughly wash what is left. They also suggested people avoid bagged lettuce and pre-mixed salad kits.
On Tuesday, the Taco Bell restaurant chain issued a statement saying it had “voluntarily and temporarily removed limited ingredients at select restaurants as a precautionary measure. We will continue to closely monitor the situation and follow the guidance of public health authorities."
In a call with reporters on Tuesday, federal health officials did not directly respond to a question about whether they are looking at Taco Bell or any specific food vendor or distributor.
“FDA certainly is continuing its traceback investigation on multiple produce items, also including locations that are reported by the case patients before they became sick,” said Donald Prater, The U.S. Food and Drug Administration's Acting Deputy Commissioner for Food, in response.
Cyclospora causes ‘explosive’ diarrhea
Cyclospora is a microscopic, spherical parasite that commonly causes watery diarrhea “with frequent and sometimes explosive bowel movements,” according to the U.S. Centers for Disease Control and Prevention. Outbreaks tend to occur most often in the late spring and summer.
The heat-loving parasite infects the bowels and spreads through feces. In the past, people have been infected by consuming fruits or vegetables that were exposed to feces-contaminated irrigation water.
The illness, called cyclosporiasis, is less common than foodborne illnesses caused by other germs, including salmonella and E. coli. Many cases are never linked to a specific food or other source and, for years, few U.S. cyclospora outbreaks were reported. But the number started rising about a decade ago, with a particularly notable spike in 2018 and 2019.
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Experts say it's likely that cyclospora cases historically were underreported, in part because some common tests used to check for food poisoning have not been geared to detect cyclospora. They attribute the increasing trend in cases to climate change and better detection.
